Process and plant for packaging fluid or semi-fluid products in thermoformable synthetic resin containers

ABSTRACT

A continuous lamina (3) is indexed through a forming station so as to be arranged around a tubular element (14); edges of the lamina (3) are welded together to form an unexpanded envelope (2a) which is then inflated when the envelope (2a) is closed in a die (11) through opposite sides of which said tubular element (14) passes; a container (2) formed by expanding said envelope (2a) is then filled and closed while a following envelope (2a) is being expanded.

The invention concerns the packaging of fluid or semi-fluid products(that is, in liquid, semi-liquid, pasty, powdery form or in small-sizedpieces) in thermoformable synthetic resin containers.

Prior art involves a process in which the chamber of the container isformed by first placing in a die two laminas of thermoformable syntheticresin in such a way that the opposing faces of the die, which surroundthe cavity of the die, heat solder the two laminas so as to create anunexpanded envelope within the cavity of the die. Immediatelyafterwards, a hot pressurized gas is introduced into the unexpandedenvelope through one or more thin conduits to expand it, pressing itssides against the internal surfaces of the die that define the externalshape of the container. Subsequently the said conduits are retracted andthe laminas are completely soldered, also in the areas through which thesaid conduits passed. Subsequently the chamber is cut in a suitable areain order to create an opening; it is then filled through the saidopening and finally the opening is re-closed by soldering in order toseal the contents.

U.S. Pat. No. 3,423,902, discloses a plant for the manufacture offlanged plastic containers in which two vertical curtains ofthermoformable plastic material are inserted in the cavity of a die, avertical tubular element being interposed between them, said tubularelement being provided with a plurality of longitudinal passages throughwhich selectively pressurized air is injected to form the container andsubsequently a filling product is introduced into the container itself.

However the container manufactured by means of said plant cannot becompletely filled with the product, because at least the presence of thetubular element in the container when the product is introduced into itprevents complete filling of the container when the tubular element iswithdrawn from it before sealing the formed container.

Furthermore, operation of said plant is quite slow, mainly because thecontainer must be filled in the same station, i.e. the die, in whichforming takes place.

The advancing downwards of the vertical curtains is produced by avertically downward stroke of the die in its closed condition, the diethen being opened and then performing an upward return stroke. Thiscycle of movement of the die is guided by roller followers cooperatingwith fixed cams.

U.S. Pat. No. 3,505,705 discloses a plant similar to that of U.S. Pat.No. 3,423,902 except that it produces flangeless containers by includingin the die electric heating elements around the outlines of the diecavities.

DE-B-1 180 301 discloses a plant which differs from those of U.S. Pat.Nos. 3,423,902 and 3,505,705 in a number of significant respects amongwhich are that the containers are formed from a tube of plasticsextruded round the vertical tubular element, that the tubular elementextends through both of the top and bottom sides of the die duringfilling of a previously formed container, and that the die is formed ofsix sections which perform a complicated cycle of movements relative toeach other and to the tubular element, which itself reciprocatesvertically.

EP-A-0 169 183 discloses a plant in-which containers are produced bycontinuous extrusion of plastics, blow-moulding of the containersbetween two loops of die sections carried upon endless conveyors, thepressurized air being introduced horizontally to form the containers andthe product being therafter introduced by way of a vertical fillingtube, the closing sealing of the container being performed between eachadjacent pair of containers at a time when the product is in a conditionoverflowing from the upper container of the pair into the next highercontainer.

U.S. Pat. No. 5,223,073 discloses a blow moulding system in whichadvancement clamps located before and after an array of moulds move twomutually facing films in a direction in which the following are arrangedin sequence: two welding half-moulds, which by mutually welding the twofilms in preset regions define cells which are open toward an upperhorizontal longitudinal edge of the films; two half-moulds for heatingthe welded films; and a cell forming station. Air injection nozzles,inserted between the two flaps of the films at the above mentionedlongitudinal edge, and two forming half-moulds, in which formingcavities are defined at the cells, operate in the forming two flaps ofthe films at the above mentioned longitudinal edge, and two forminghalf-moulds, in which forming cavities are defined at the cells, operatein the forming station. Divaricators for divaricating the two flaps ofthe films are provided proximate to the forming station so as tofacilitate the insertion of the air injection nozzles.

A first object of the invention is to find a process which is generallymore economical and rational, is quicker and permits the container to becompletely filled (leaving no air).

A further object of the invention is to find a process which is moresuited to the packaging of products in a sterile manner, preventingcontact of the chamber with the surrounding air and also preventingshards of material, produced when the container is cut in order tocreate an opening, from falling into the chamber itself: this being adrawback of some of the prior art.

Said objects and other objects are reached by the invention as definedin the claims.

According to one aspect of the present invention, there is provided aprocess for packaging fluid or semi-fluid products in thermoformablesynthetic resin containers, each defining an internal chamber,comprising forming around tubular means a continuous hollow member ofthermoformable synthetic resin, bringing together sections of a die toreceive said hollow member between them and thereby to encircle saidtubular means and to define a desidered external shape of a container,forming a chamber in said hollow member by injection of pressurizedfluid through said tubular means, filling the container with a productthrough said tubular means, and sealing the container, characterized inthat said continuous hollow member is formed by bringing together andsealing parts of at least one web of said thermoformable syntheticresin, which parts correspond to outlines of the containers.

According to a second aspect of the present invention, there is provideda plant, suitable for carrying out the process defined above, comprisinga forming station with a die having at least two complementary hollowsections that, combined, form a cavity defining the external shape ofthe container, tubular means providing forming means to injectpressurized fluid into said cavity to form a chamber of defining theexternal shape of the container, tubular means providing forming meansto inject pressurized fluid into said cavity to form a chamber of thecontainer and filling means to introduce the product into the chamber,and sealing means to close the filled container, said tubular meansextending in a separation plane of the die, characterized in that theplant includes, ahead of said forming station, roll means whereby the oreach web is fed towards said forming station.

Embodiments of the invention are illustrated in the following foursheets of drawings.

FIG. 1 is a general schematic representation of a first embodiment ofthe plant.

FIG. 2 is an enlarged detail of FIG. 1.

FIG. 3 is section III--III of FIG. 2.

FIG. 4 is section IV--IV of FIG. 2

FIG. 5 is the axial section of FIG. 2

FIG. 6 is a schematic representation of a second embodiment of theplant.

FIG. 7 is a schematic representation of forming station 10 in a furtherembodiment.

The plant includes a forming station 10 with a die 11 including twocomplementary hollow sections 11b, or halves, whose cavity 12 definesthe shape of chamber 2 of the container. The hollow sections 11b,respectively, have matching faces 11a that close cavity 12, and whichare preferably arranged in an essentially vertical separation plane.

A tubular element 14 passes through at least the upper part of cavity 12preferably with an essentially vertical axis and placed in theseparation plane between sections 11b. In the embodiments illustrated inthe figures, the tubular element 14 crosses cavity 12 and extends beyondit both above and below it.

Upstream of the die 11 feeding means are provided to supply a continuouslamina of heat solderable resin in such a way as to cover the tubularelement 14 and to form around it an unexpanded envelope 2a within cavity12 (FIG. 3).

The embodiment illustrated in FIGS. 1 to 5 comprises feeding means,particularly two spools 31 from which, respectively, two continuoussheets 32 of heat solderable resin lamina 3 are unrolled, said sheetspassing through sterilization means 60 and heating means 65;subsequently said sheets, parallel and in contact with each other, passbetween the hollow sections 11b of the die, with tubular element 14between them.

Each hollow section 11b is provided with two symmetrically distributedrecesses 13 (FIG. 4), having a preferably semi-cylindrical shape, oneabove and one below, defining two cylindrical through-holes allowing thetubular element 14 to pass through the sides of die 11. The recesses 13matching together when the hollow sections fit around tubular element14.

The die 11 presses the two sheets 32 together by means of its faces 11aand solders said sheets in the respective areas of contact by means ofheat produced by suitable heating elements, such as electricresistances.

Furthermore, the recesses 13 also press the sheets 3 against those partsof the tubular element 14 that pass through the sides of die 11. Thus,the two sheets 32 inside the cavity 12 make up the unexpanded envelope2a, which is hermetically sealed by the joining of the two faces 11a andby the recesses 13 fitting around the tubular element 14.

The forming station 10 is also provided with forming means to introducepressurized fluid, in particular sterile air, into the envelope 2a whenit is closed by-the die 11 and the tubular element 14, that causes it toexpand until its sides adhere to the walls of the cavity 12, therebyobtaining the final shape of the chamber 2.

Said forming means can preferably be defined by the tubular element 14itself, communicating, above, with means (not shown) that supply thepressurized air, and inside with the cavity 12 by means of openings 15.

With each forming cycle of the chambers 2, the die 11 is closed aroundthe sheets 32 in contact with each other and which enclose the tubularelement 14; thus, edges 32a of sheets 32 around cavity 12 are soldered,whereas they are not soldered in the areas that are in contact with theelement 14, though they are kept pressed against it thereby keeping theenvelope 2a closed; the pressurized air is then introduced into theenvelope 2a through the tubular element 14 and the envelope 2a expandsand becomes permanently shaped by cavity 12. The resulting chamber hasan upper hole 21 and a lower hole 22, preferably of the same diameter,due to the presence of the tubular element 14 at the points where itpasses through the sides of the die.

After each forming cycle, the die 11 is opened and, by means ofappropriate driving means (such as motorized rollers 19), the laminas 3,together with the chamber 2, are advanced downwards a distance equal tothe vertical length of the die 11, or a little less. In this way,advancing alternately with the forming cycles, a continuous strip iscreated in the laminas 3, advancing downwards, that consists of aplurality of chambers 2 communicating with each other by means ofcontiguous openings 21 and 22 in the lower part of each chamber 2 and inthe upper part of the next chamber 2 below it.

Beneath the forming station 10 the plant includes a soldering station40. The chambers 2, as soon as they have been formed, are moved on withintermittent motion, alternately with the forming cycle (or even with acontinuous motion), arriving first at an intermediate position A,beneath the die 11, and subsequently on to the soldering station 40,where by means of soldering means 41, an upper opening 21 of the chamber2 that is positioned in the soldering station 40 and a lower opening 22of the chamber 2 above it are closed by soldering.

The product 9 to be packaged is introduced in the succession of chambers2 through the tubular element 14 whose lower outlet is in theintermediate position A.

In particular, as illustrated in FIGS. 1 to 5, between the chambers 2positioned in stations 10 and 40, there is at least one chamber 2 in theintermediate position A.

The product 9 is preferably supplied through a filling conduit 23 thatpasses through the entire length of the tubular element 14 and whichcommunicates above with filling means (of conventional type and notshown) that supply the product, whilst at the bottom end, the outlet isbeneath the die 11.

Said supply can be continuous or intermittent.

Inside the tubular element 14 a breather conduit 24, or vent, isprovided to enable the air to be expelled during the introduction ofproduct 9. In each of the positions where the tubular element 14 passesthrough the sides of the die 11 a collar 16 (FIG. 4) is provided tostiffen the tubular element 14 against the pressure of the die 11. Anupper collar 16 positioned in an upper part (FIG. 4) of the die 11 iscrossed by conduits 23 and 24 and by holes 17 that enable the passage ofpressurized air; a lower collar 16 at a lower part of the die is crossedonly by conduits 23 and 24 and blocks the passage of the pressurized airsince the latter must only be introduced in the cavity 12.

In order to completely fill the chamber 2, the supply of the product 9is such that when the chamber 2 is in the soldering station 40 andbefore its upper opening 21 is soldered the level of the product 9 isabove the opening 21 (as illustrated in FIG. 5). At this point thesoldering means 41 close both opening 21 and the opening 22 of chamber 2above it. Then, as the strip of chambers 2 is lowered one step, thechamber 2 in the intermediate position A moves into the solderingstation 40 and, after the level of the product has once again risenabove its opening 21, this opening is also closed as described above.

It is to be noted that with each closure of upper opening 21, the loweropening 22 above it is also closed, which permits the successive chamber2 to be filled.

It is advantageous for the soldering cycles to occur at the same time asthe forming cycles while the strip of chambers 2 is stationary.

In the intermediate position A, between the forming station 10 and thesoldering station 40, a number of chambers 2 may be provided so as toform a larger volume to be filled with the product 9.

It is to be understood that, when sealing of the container takes placein the soldering station 40 by activation of the soldering means 41, theproduct may partially fill the chamber 2 in the intermediate position A,thereby preventing the presence of air in the sealed container, thelatter having been constantly kept under an hydrostatic head determinedby the excees of product.

The separation of each chamber 2 from the strip can take place in thesoldering station 40 after it has been filled and closed with solderingmeans 41. This can occur by cutting the strip along a line T in a medianposition along the soldering area so as to leave both upper opening 21of the chamber 2 containing the product 9 and lower opening 22 ofchamber 2 above it closed. At the same time as cut T, cutting means 42can carry out a contouring cut along line R in order to separate part ofthe soldered edge from chamber 2 to give the container the desiredshape.

In this way the finished container is obtained, containing product 9,separated from the strip of chambers 2 and appropriately contoured. Thefinal container obtained can be of any known type that can be obtainedby means of injection of heated gas with resulting thermoforming. Forexample, at the same time as the cut along line T is made, it ispossible to incorporate a line of weakness close to the upper opening 21that enables it to be opened by the user.

The shape of the container may be different from the shape shown in thedrawings: for instance the container may be provided with asupplementary opening distinct from the opening 21 that enables it to beopened by the user.

The two sheets 32 can be unwound from two separate spools 31 (asillustrated in FIG. 1) or from a single spool on which the sheet hasalready been folded longitudinally. According to an alternativeembodiment, the sheet can be folded after it has been unwound from thespool so as to have two sheets side by side in contact with each other.The longitudinal fold line of sheets 32 can pass through cavity 12without being pressed between faces 11a of the die.

In a further embodiment, illustrated in FIG. 6, there is a single spool33 from which a single sheet 34 is unwound by means of known guidingdevices (not shown); it is folded so as to wrap around tubular element14 with the edges of sheet 34 overlapping each other in a longitudinaldirection; said edges are then soldered together, for example, byheating them with hot air supplied through a tube 36 and pressing themtogether against tubular element 14 using roller 37. In this way acontinuous cylindrical sheath is obtained wrapped closely around thetubular element 14 which is led through die 11 where it forms theunexpanded envelope 2a; said cylindrical sheath is then closed by thecontact with recesses 13 that press it against the external surface ofthe tubular element 14. The subsequent forming of chambers 2 usingpressurized hot air and the successive steps of the process are the sameas described above.

FIG. 7 illustrates still a further embodiment of the forming station 10which differs from that illustrated in FIG. I in that the pressurizedgas is introduced in the envelope 2a through channels 27 formed betweenthe two sheets 32 by corresponding grooves in the faces 11a.

After the die has been closed air is injected into envelope 2a usingtubes 26 and through channels 27 to form the chamber 2. Then, usingsoldering means 28, the channels 27 are also closed. In this case, onlyfeed conduit 23 and the breather conduit 24 pass through the tubularelement 14.

The invention is suitable for packaging products in a sterile manner.Firstly, it is simple and easy to sterilize sheets 32 using sterilizingmeans 60, for example, consisting of a dip 61 in sterilizing liquidand/or heating means 65. Furthermore, the forming of the chamber 2 canbe carried out using sterile gas and in the following steps, havingenclosed the die in a simple protective casing 63, the internal surfaceof chamber 2 does not come into contact with the outside environment andso cannot be contaminated by it. Casing 63 can be a simple cover thatencloses the die 11 and the sheets 32 and in which a sterile environmentis maintained with a slight excess pressure.

In still a further embodiment not shown in the figures, the tubularelement 14 passes through only the upper side of die 11 and not throughthe bottom side of it. During forming, then, chambers 2 are obtainedthat only have upper opening 21, product 9 is introduced through thetubular element 14 and, after having removed the chamber from tubularelement 14, opening 21 is closed by soldering.

I claim:
 1. Process for packaging fluid or semi-fluid products inthermoformable synthetic resin containers each defining an internalchamber, comprising providing around tubular means at least onecontinuous web of thermoformable synthetic resin, bringing togethersections of a die to receive the at least one web between them andthereby to encircle said tubular means with said die having oppositeentry and exit sides for said at least one web, and to seal togetherparts of said at least one web, which parts correspond to outlines ofthe containers, to define a desired external shape of the containers,forming a chamber in said at least one web by injection of pressurizedfluid through said tubular means, filling the container with a productthrough said tubular means, and sealing the container, wherein saidtubular means extends through both of said entry and said exit sides ofsaid die throughout said process.
 2. Process as claimed in claim 1,wherein the advancing condition of said at least one web alternates withthe closed condition of the die.
 3. Process as claimed in claim 1,wherein said at least one web is advanced by pullingly engaging said atleast one web beyond said die.
 4. Process as claimed in claim 1 andfurther comprising, after said forming of the chamber and before saidfilling of the container, removing the container from the diecompletely, said filling of the container comprising introducing theproduct into the chamber through said tubular means.
 5. Process asclaimed in claim 1, wherein a downwardly extending continuous strip isformed in said at least one web with a succession of chambersintercommunicating with each other through contiguous openings in thetops and bottoms of the chambers of each pair of adjacent chambers, saidopenings being formed by the presence of said tubular means that extendsdownwardly through said opposite sides of the die.
 6. Process as claimedin claim 5, wherein the chambers, after being formed, are moveddownwards while still joined together in said strip and each chamber ismoved firstly to an intermediate position beneath the die, and then onto a sealing station where the upper opening of a full chamber and thelower opening of the chamber above it are closed by sealing, theintroduction of the product taking place in the succession of chambersthrough the tubular means, the lower outlet of which is in theintermediate position.
 7. Process as claimed in claim 1, wherein asingle web is wrapped round the tubular means so that the edges of theweb overlap each other longitudinally, said edges subsequently beingsealed together so as to form a continuous cylindrical hollow memberround the tubular means, said hollow member extending through the diewhere it provides an unexpanded envelope and where it is closed by thedie pressing the hollow member against the tubular means.
 8. Process asclaimed in claim 7, wherein the sealing together of said edges includespressing of said edges against said tubular means.
 9. Plant, suitablefor carrying out a process of packaging fluid or semi-fluid products insynthetic resin containers, comprising roll means whereby at least oneweb of thermoformable synthetic resin is fed, after said roll means aforming station with a die having at least two complementary hollowsections that, move together to, form a cavity defining the externalshape of a container and to seal together at least parts of said atleast one web, said die having an entry side and an exit side for saidat least one web, and encircling a tubular means providing forming meansto inject pressurized fluid into said cavity to form a chamber of thecontainer and filling means to introduce a product into the chamber, andsealing means to close the filled container, said tubular meansextending in a separation plane of the die, wherein said tubular meansis arranged to extend through both said entry side and said exit sidethroughout said process.
 10. Plant as claimed in claim 9 and furthercomprising driving means disposed after said die for engaging andadvancing said at least one web.
 11. Plant as claimed in claim 10,wherein said driving means comprises motorized rollers.
 12. Plant asclaimed in claim 9, and further comprising pressing means that pressesoverlapped longitudinal edges of a single web against the externalsurface of the tubular means, and heating means that heats said edges toseal them together.
 13. Plant as claimed in claim 9, wherein saidtubular means is provided with upper and lower internal collars, theupper collar allowing the passage of the pressurized fluid and of theproduct, and the lower collar allowing the passage of the product only.14. Plant as claimed in claim 9, wherein said filling means extendslongitudinally axially of said at least one web and said forming meansextends transversely of said filling means.